US3700437A - Transparent imaging medium - Google Patents

Transparent imaging medium Download PDF

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Publication number
US3700437A
US3700437A US76279*[A US3700437DA US3700437A US 3700437 A US3700437 A US 3700437A US 3700437D A US3700437D A US 3700437DA US 3700437 A US3700437 A US 3700437A
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United States
Prior art keywords
transparent
film
pellucid
semiconductor
coating
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Expired - Lifetime
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US76279*[A
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English (en)
Inventor
William E Eastler Jr
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Northrop Grumman Guidance and Electronics Co Inc
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Itek Corp
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
    • G03C1/00—Photosensitive materials
    • G03C1/705—Compositions containing chalcogenides, metals or alloys thereof, as photosensitive substances, e.g. photodope systems
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
    • G03C1/00—Photosensitive materials
    • G03C1/76—Photosensitive materials characterised by the base or auxiliary layers
    • G03C1/7614—Cover layers; Backing layers; Base or auxiliary layers characterised by means for lubricating, for rendering anti-abrasive or for preventing adhesion
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G5/00—Recording members for original recording by exposure, e.g. to light, to heat, to electrons; Manufacture thereof; Selection of materials therefor
    • G03G5/02—Charge-receiving layers
    • G03G5/04—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor
    • G03G5/08—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor characterised by the photoconductive material being inorganic
    • G03G5/087—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor characterised by the photoconductive material being inorganic and being incorporated in an organic bonding material
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G5/00—Recording members for original recording by exposure, e.g. to light, to heat, to electrons; Manufacture thereof; Selection of materials therefor
    • G03G5/14—Inert intermediate or cover layers for charge-receiving layers
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G5/00—Recording members for original recording by exposure, e.g. to light, to heat, to electrons; Manufacture thereof; Selection of materials therefor
    • G03G5/14—Inert intermediate or cover layers for charge-receiving layers
    • G03G5/147—Cover layers
    • G03G5/14704—Cover layers comprising inorganic material
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G5/00—Recording members for original recording by exposure, e.g. to light, to heat, to electrons; Manufacture thereof; Selection of materials therefor
    • G03G5/14—Inert intermediate or cover layers for charge-receiving layers
    • G03G5/147—Cover layers
    • G03G5/14708—Cover layers comprising organic material
    • G03G5/14713—Macromolecular material
    • G03G5/14747—Macromolecular material obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G5/00—Recording members for original recording by exposure, e.g. to light, to heat, to electrons; Manufacture thereof; Selection of materials therefor
    • G03G5/14—Inert intermediate or cover layers for charge-receiving layers
    • G03G5/147—Cover layers
    • G03G5/14708—Cover layers comprising organic material
    • G03G5/14713—Macromolecular material
    • G03G5/14795—Macromolecular compounds characterised by their physical properties

Definitions

  • a photographic imaging medium comprising a transparent support, a pellucid film of a particulate photosensitive semi-conductor thereon preferably having a thickness of about /2 mil or less, and a transparent film over said pellucid film to decrease light diffraction thereby.
  • the semiconductor preferably has an average particle size of about 300 mp. or less in diameter and preferably is present on the imaging medium in an amount per unit area of about 3 grams per square meter (g./m. or less.
  • the present invention relates to methods for reducing light diffraction in a pellucid photographic imaging medium and to improved pellucid imaging media exhibiting reduced light diffraction.
  • the photosensitive semiconductors described in the copending application which materials are also photoconductors, are principally compounds formed between metals and elements of Group VI of the Periodic Table, namely metal oxides, sulfides, selenides, and tellurides.
  • Imaging media including similar photosensitive materials are taught in US. 3,052,539 for use in electrostatic image forming processes.
  • Imaging media of particular interest because they can be used to prepare positive or negative photographic transparencies, are those prepared by supporting a photosensitive material on a transparent base. To prepare such imaging media, finely-divided particles of a photoconductor are conveniently dispersed in a binder and applied as a thin film to a transparent substrate.
  • the photoconductors of interest are commonly materials of relatively high refractive index. Indeed, titanium dioxide, which is a material of particular interest, has the highest index of refraction of any known substance. As a result, light is strongly diffracted at the surface of the light-sensitive film on the transparent support. This tends to increase the opacity of the resulting media, rendering them less suitable for the preparation of transparencies.
  • diffraction of light at the surfaces of such an imaging medium can be significantly reduced by coating the photosensitive layer with a transparent coating such as a resinous material.
  • the difference between the refractive index of the coating and that of the photosensitive semiconductor should be less than the difference between the refractive indices of the photo sensitive semiconductor and the viewing atmosphere, e.g. air.
  • the difference between the indices of refraction of the semiconductor compound and the coating should preferably not be more than about 1.0 unit and more preferably not more than about 0.5 unit.
  • Low density information is that information having a density of .03- .05 density unit above base plus fog.
  • the semiconductor has an average particle size of about 300 m or less in diameter, preferably the semiconductor is present on the imaging medium in an amount per unit area of about 3 grams per square meter or less, the semiconductor layer preferably has a thickness of about /2 mil or less and more preferably about 2 microns or less, and the photoconductor preferably is properly dispersed in the binder material, as for example by means of a sonic blender.
  • FIG. 1 is a perspective view of an imaging medium of the present invention comprising a transparent support, a photosensitive semiconductor layer, and a transparent resin coating reducing light diffraction.
  • transparent substrate materials suitable for use in preparing the imaging media of the present invention support layers of materials such as cellulose acetate, polystyrene, polyacetates, polyesters, glass, or glassine-type papers made from highly beaten wood pulps may be employed.
  • the photosensitive semiconductors or photoconductors preferred in this invention are metal containing photoconductors.
  • a preferred group of such photosensitive materials are inorganic materials such as the compounds of a metal and a non-metallic element of Group VI-A of the Periodic Table, e.g. oxides such as zinc oxide, titanium dioxide, zirconium dioxide, germanium dioxide, and indium trioxide; metal sulfides such as cadmium sulfide (CdlS), zinc sulfide (ZnS), and tin disulfide (SnS and metal selenides such as cadmium selenide (CdSe).
  • CdlS cadmium sulfide
  • ZnS zinc sulfide
  • SnS and metal selenides such as cadmium selenide (CdSe).
  • Titanium dioxide is a preferred metal oxide because of its sensitivity, availability, and color. Titanium dioxide which has an average particle size less than about 250 millimicrons is preferred. Especially preferred also is titanium dioxide which has been treated in an oxidizing atmosphere at a temperature between about 200 C. and 950 C. for from about 0.5 hour to about 30 hours, and more especially that titanium dioxide produced by high temperature pyrolysis of a titanium halide.
  • Imaging media made with titanium dioxide are particularly amenable to improvement according to the present invention in view of the high index of refraction 1 (2.5) of the material when compared, for example, with that of air (1.0) because of the particulate and opaque appearance of the photoconductor in the photosensitive layer, the latter is usually not absolutely clear.
  • This layer is characterized herein as being pellucid to suggest a character intermediate to absolute transparency and translucency.
  • the refractive index of the coating for the semiconductor of this invention will be between that of air and that of the photosensitive semiconductor due to the high indices of refraction of the photosensitive semiconductors.
  • the photoconductors present in the imaging media of this invention may be sensitized to visible and other wavelengths of light by foreign ion doping, addition of fluorescent materials, and/or by means of sensitizing dyes.
  • Bleachable dyes useful for sensitizing the photoconductors of this invention include, for example, the cyanine dyes, the dicarbocyanine dyes, the carbocyanine dyes, and the hemicyanine dyes. Additional dyes which are useful for sensitizing the photosensitive medium of this invention are the cyanine dyes described on pp. 371-429 in The Theory of Photographic Process, by C. E. Kenneth Mees, published by McMillan Company in 1952.
  • Trihenylmethane dyes such as crystal violet and basic Fuchsin, diphenylmethane dyes such as Auroamine O, and Xanthene dyes such as Rhodamine B.
  • the photoconductors are usually dispersed as finelydivided particles in a binder which is preferably chosen to have a high index of refraction approaching that of the particles dispersed therein.
  • a binder which is preferably chosen to have a high index of refraction approaching that of the particles dispersed therein.
  • Gelatin the commercially available Rhoplex" acrylates, acid-soluble acrylics, and styrene-butadiene resins have all been employed in the art as binder materials.
  • the pigment to binder ratio may be between 1:4 and 16:1 and is preferably between 2:'1 and 12:1. In coatings containing a given weight of pigment, optimum transparency is observed, surprisingly, when the pigmentzbinder ratio is about 6:1.
  • the addition of further binder although diluting the pigment in the coating, increases the opacity of the coating.
  • the particle size of the photosensitive semiconductor is preferably about 300 millimicrons or less in average diameter since films made using this particle size have much improved
  • the photosensitive semiconductor may be treated prior to exposure to imaging radiation with an agent forming an image on exposure.
  • a photosensitive material such as titanium dioxide may be treated with reducible metal ions prior to imaging exposure.
  • a latent or visible image is formed, depending on exposure conditions and the substances employed. Latent images may be intensified to make them visible, for example by techniques analogous to physical development, as mentioned hereinbefore.
  • Imaging media comprising a supported photoconductor layer of this type may be developed after exposure to imaging radiation by contact with image-forming agents which, for example, react chemically at the light-sensitized semi-conductor surfaces to form materials defining an image.
  • image-forming agents are commonly easily reducible substances such as metal Determined by means of sodium light (5893 angstroms).
  • the ions react to form free metal at activated semiconductor sites to define the image.
  • the images may suitably be intensified using techniques analogous to physical development.
  • electrostatically responsive powders which conform to an electrostatic charge pattern on the media to define an image can be used for development. Prints of this type are commonly fixed by fusing the powders to the substrate on which they are supported.
  • the transparent resinous coatings which are applied according to the present invention to the photosensitive layer of an imaging medium may be applied to the medium before or after its exposure and development. If the transparent coatings are applied before chemical development, however, a transparent coating material must be chosen which will be permeable to the image-forming developing agents employed. The latter are generally aqueous, but not exclusively so.
  • the transparent overcoatings applied to the underlying photosensitive layer are substantially transparent film forming materials and include organic and inorganic coatings such as synthetic or natural film-forming materials and include synthetic resins such as butadienestyrene copolymers, e.g. those available commercially under the trade name Pliolite; film-forming polyacrylate resins such as those sold under the trade name Tamol; and natural materials such as gelatin.
  • Organic and inorganic coatings such as synthetic or natural film-forming materials and include synthetic resins such as butadienestyrene copolymers, e.g. those available commercially under the trade name Pliolite; film-forming polyacrylate resins such as those sold under the trade name Tamol; and natural materials such as gelatin.
  • Metal oxides such as titanium dioxide may be deposited as transparent films by vacuum deposition techniques and the like.
  • the thickness of the transparent coating is not of significance to the present invention providing, however, that the coating is permeable to chemical developing agents if the coating is applied to a photosensitive
  • the thickness of the coating should be sufiicient to completely cover any photosensitive semiconductor particles and to thereby form a smooth surface on the copy medium.
  • the formation of a substantially smooth surface is important to obtain maximum transparency according to this invention.
  • These overcoatings are not photosensitive per se. They comprise photochemically inert materials which are retained on, or are applied to, an image-bearing print, and are generally not temporary coatings removed during developing or fixing operations.
  • the refraction index of these coatings is very close or the same as that of photosensitive semiconductors.
  • the top coating for a titanium dioxide layer, the titanium dioxide having a refractive index of about 2.5 preferably has a refractive index of from about 1. 5 to 2.5.
  • the photosensitive semiconductor layer of this invention may be a separate layer apart from the transparent support.
  • the photosensitive semiconductor may be incorporated in a resinous binder.
  • the photosensitive semiconductor particles may be incorporated in the transparent support or may be deposited on the surface of such support.
  • FIG. 1 shows a typical pellucid imaging medium prepared according to the present invention comprising a transparent support layer of clear cellulose triacetate 4 to 6 mils thick, subbed with resin or gelatin, and having a light transmission of foot candles.
  • This support is subsequently roll-coated with a lightsensitive layer comprising an aqueous mixture of a photoconductor and binder containing 6 percent of solids and,
  • the pigment is a commercially available titanium dioxide having a mean diameter of 0.03 micron.
  • the binder comprises a mixture of 1 part of lime bone, low bloom, low viscosity, subbing type gelatin with 3 parts of lime bone, high bloom inert photographic-type gelatin.
  • the layer applied has a thickness of about 0.1 mil, corresponding to about 2 pounds/ 3000 square feet.
  • Additives which may optionally be present in the light-sensitive layer include wetting agents and dispersants which aid in preventing agglomeration of the photoconductor particles, thus improving transparency of the coating.
  • the top coat which has a thickness of less than 0.1 mil, is lime bone inert gelatin deposited from a 1.5-2.5 percent aqueous solution.
  • the finished medium can be exposed to light and developed by contact with aqueous silver nitrate.
  • Imaging media prepared as in this example but without a top coat generally have a transmission between 4 and 75 foot candles, compared with 100 for the uncoated sup port material.
  • a film-forming material e.g. a polyacrylate resin such as the Tamol commercial resin earlier mentioned
  • the transmission of the film can be brought back up to about 90 foot candles.
  • gelatin is a preferred material because of its permeability to aqueous solutions used to develop the media.
  • the transparency of the media can also be increased by decreasing the quantity of particulate semiconductor present, but this in turn decreases the sensitivity of the media and the image densities attainable therewith.
  • a transparent photographic film comprising: (1) a transparent substrate, ('2) a thin pellucid film thereon comprising a particulate photoconductor selected from the group consisting of zinc oxide and titanium dioxide, and wherein the photoconductor has an average particle size of about 300 m or less in diameter and (3) a transparent coating over said pellucid film; the transparent coating having a refractive index such that the dilference between the refractive indices of the coating and that of the photoconductor is less than the ditference between the indices of refraction of the viewing atmosphere and that of the photoconductor.
  • a medium as in claim 1 wherein the transparent coating is permeable to an image forming developing agent comprising an aqueous solution of metal ions.
  • a medium as in claim 1 wherein said photoconductor is zinc oxide.
  • a medium as in claim 1 wherein said photoconductor is titanium dioxide.
  • the index of refraction of said transparent coating has a value such that the difference between the indices of refraction of the coating and that of the photoconductor is less than about 1.0 unit.
  • the method of decreasing diffraction at the surface of a photographic imaging medium comprises roll coating onto a transparent substrate, a pellucid film comprising a particulate photoconductor selected from the group consisting of zinc oxide and titanium dioxide, and wherein the particle size of the photoconductor is about 300 me or less and coating said pellucid film with a transparent coating having an index of refraction such that the difference between the refractive indices of the coating and that of the photoconductor is less than the difference between the indices of refraction of the viewing atmosphere and that of the photoconductor.
  • the method of decreasing diffraction at the surface of a photographic imaging medium which comprises roll coating a transparent substrate with a thin pellucid film of a particulate titanium dioxide wherein the titanium dioxide has a particle size of about 300 mg or less, and coating the pellucid film of titanium dioxide with a transparent coating having an index of refraction close to or the same as that of the titanium dioxide.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Materials Engineering (AREA)
  • Inorganic Chemistry (AREA)
  • Metallurgy (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Photoreceptors In Electrophotography (AREA)
  • Non-Silver Salt Photosensitive Materials And Non-Silver Salt Photography (AREA)
US76279*[A 1968-02-27 1970-12-21 Transparent imaging medium Expired - Lifetime US3700437A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US70863068A 1968-02-27 1968-02-27
US7627970A 1970-12-21 1970-12-21

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US3700437A true US3700437A (en) 1972-10-24

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US (1) US3700437A (xx)
BE (1) BE728902A (xx)
DE (1) DE1909993A1 (xx)
FR (1) FR2002721A1 (xx)
GB (1) GB1252974A (xx)
NL (1) NL6902824A (xx)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4482624A (en) * 1983-02-15 1984-11-13 The Mead Corporation Photosensitive material employing encapsulated radiation sensitive composition and process for improving sensitivity by sequestering oxygen
US4973537A (en) * 1984-05-15 1990-11-27 Fuji Photo Film Co., Ltd. Photoconductive element
US20140235752A1 (en) * 2011-05-17 2014-08-21 Columbia Insurance Company Self-Coalescing Latex

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4482624A (en) * 1983-02-15 1984-11-13 The Mead Corporation Photosensitive material employing encapsulated radiation sensitive composition and process for improving sensitivity by sequestering oxygen
US4973537A (en) * 1984-05-15 1990-11-27 Fuji Photo Film Co., Ltd. Photoconductive element
US20140235752A1 (en) * 2011-05-17 2014-08-21 Columbia Insurance Company Self-Coalescing Latex
US9505922B2 (en) * 2011-05-17 2016-11-29 Columbia Insurance Company Self-coalescing latex

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Publication number Publication date
NL6902824A (xx) 1969-08-29
BE728902A (xx) 1969-08-25
GB1252974A (xx) 1971-11-10
DE1909993A1 (de) 1969-09-18
FR2002721A1 (xx) 1969-10-31

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